1. Field of the Invention
The present invention relates generally to internal combustion engines, having intake and exhaust valves that are linearly actuated by camshaft means, and with said camshaft means having a timing gear or timing sprocket means removably attached thereto. Said engine also having linearly reciprocating piston means, and connected to a crankshaft, which has a suitable driving gear means thereon in a predetermined fixed phase to said timing gear means. More specifically, this invention pertains to methods and mechanisms which are used for automatically varying and/or governing the phased timing of opening and closing of the intake and exhaust valves of said engine.
2. Description of the Prior Art
State of the art valve timing-varying means which are provided for liquid and/or gas fuel burning internal combustion engines especially those which are utilized for but not limited to those providing vehicular locomotion, are the performance compromised product of engine technologies, prevailing economic factors and environmental constraints. These engines depend on high component-density electronic subsystems for their overall performance and for controlling the function of complex electromechanical, or hydro-mechanical subsystems or selected combinations thereof, to vary the opening and closing times of valves relative to the angular position of the crankshaft. While these systems improve fuel efficiency and engine performance, they are beset with problems which are characteristically inherent in complex high component-density system designs. The advantages gained are frequently offset by system failure, due to the high rate of subsystem component malfunctions. In prior arts U.S. Pat. No. 3,978,829 Takahashi, and U.S. Pat. Nos. 4,494,495, 496, and 4,561,390 Nakamura et al. are noted complex, subsystem-interdependent and highly component-dense systems, that are costly to manufacture and maintain. Along with added electronic controls, they are also excessively bulky and further with their substantial overhanging rotating weight, they expand the engine size and weight envelope to accommodate the additional loads. Heavy dependence on automotive electronics for control functions is also evident in the art of U.S. Pat. No. 4,754,727 Hampton. This system further expands the long list of engine performance related electronic controls and adds to the cost of manufacture and general maintenance. In hydro-mechanical art disclosed in U.S. Pat. No. 4,627,825 Bruss et al., overall functional reliability is greatly reduced by the added number of electronic components required to control and monitor the operation of the device. Also, the costs of manufacture and general maintenance is escalated. Similarly, U.S. Pat. No. 4,535,731 Banfi, and U.S. Pat. No. 4,787,345 Thoma, disclose enmeshed straight and helical splines in various combinations for transferring axial action into angular displacement. However, they too are among the high component-density systems, and as such are plagued by the same high-cost to benefit ratio problem as the above referred art of Takahashi and Nakamura. For an all hydraulically operated device, as disclosed in U.S. Pat. No. 4,858,572 Shirai et al. the plurality of vanes lack the positive seals needed to maintain precise angular position under any operating condition.